Monoamine oxidase B (MAOB) is an enzyme involved in the metabolism of dopamine. It converts dopamine to its corresponding carboxylic acid via an aldehyde intermediate. MAOB regulates both the free intraneuronal concentration of dopamine and the releasable stores. MAOB inhibitors bind to and inhibit MAOB, preventing dopamine degradation. This results in greater stores of dopamine available for release. MAOB inhibitors are used in the treatment of depression. People with depression have higher levels of the brain protein MAOB that people without depression.